$ sudo npm install bn.js
$ sudo npm install -g bn.js

If want to update the bn.js package execute the command as below,

$ sudo npm update bn.js

Update package globally,

$ npm install -g bn.js

Git clone:

$ sudo  git clone https://github.com/rektide/bn.js.git

$ sudo  npm install -g ./bn.js

bn.js@4.11.8 /usr/lib/node_modules/bn.js

How to remove bn.js package :

You can uninstall or remove this package from your node_modules run the command as below,

$ sudo npm uninstall bn.js

Basic Information of bn.js NPM Package: